Today: DCDC additional topics Review voltage loop design Power MOSFET: another power semiconductor switch Emerging power semiconductor devices technologies Introduction to thermal management Conclusions 1
Voltage control loop Incorporating the inner current control loop Voltage loop gain T v Compensator design G cv S 2 voltage sensing I bus + + i bat L i L current sensing c 2 + v ge2 _ Q 2 D 2 v s C i c v bus S 1 v bat _ c 1 + v ge1 _ Q 1 D 1 _ HV ref + _ G cv + R s i ref R s i L _ G ci v c c 2 PWM c Dead-time Pulse-width modulator c 1 Hv bus H 2
Voltage control loop: loop gain Hv ref + _ G cv R s i ref i L G i /R s G vi v bus H 3
4 zi z vio i v L bus vi s s G i v G bus bat 1 1 ˆ ˆ 0 ˆ 0, ˆ bus bus vio I V D G ' bus bus z I V L D f 2 ' 2 1 bus bus zi V I C f 1 2 1 2.8 khz 19 Hz Same numerical example 16.5 db.7 6
Voltage loop compensator Gcv design Start from uncompensated loop gain, G cv = 1 T v, uncomp HG i 1 R s G vi 0-20 Bode Diagram Example Converter parameters f s = 20 khz L = 150 H C = 500 F V M = 1 R s = 1 H = 1/100 DC operating point: V bus = 500 V I bus = 30 A V bat = 200 V D = 1 V bat /V bus = 0.6 I L = I bus /D = 75 A Magnitude (db) Phase (deg) Phase (deg) -40-60 -80-100 -120 360 0 270 90 180 20log T v, uncomp( j) T ( v, uncomp j) 270 90 3600 10 0 10 1 10 2 10 3 10 4 Frequency (Hz) 5
G cp Loop gain with Proportional Integral (PI) compensator ( s) f zv f cv K pv / 5 1 s zv 60 40 Bode Diagram f cv 200 Hz m 77 o Magnitude (db) 20 0-20 -40-60 360 0 Phase (deg) Phase (deg) 90 270 180 180 270 90 3600 10 0 10 1 10 2 10 3 10 4 Frequency (Hz) 6
Closed loop response G v with PI compensator G v vˆ vˆ bus ref Tv 1T v 60 Bode Diagram 40 Magnitude (db) 20 0-20 -40-60 360 0 Phase (deg) Phase (deg) 90 270 180 270 90 3600 10 0 10 1 10 2 10 3 10 4 Frequency (Hz) 7
30A to +30 step i bus (t) transient Transient response Step d 250 Vbat Battery Voltage ibus vbus Vbat d il Averaged Boost Converter Dynamic Model vbus il 1/100 H Scope PID(s) PID(s) 6 Duty cycle limits current-loop compensator Gci Inductor current limits voltage-loop compensator Gcv Bus voltage reference Inductor (battery) current limits 200A, +200A 8
d v bus i L 9
d v bus i L 10
Power MOSFETs Textbook Section 4.2.2 11
MOSFET vs IGBT MOSFET No conductivity modulation via minority carrier injection Faster switching, no current tailing, much smaller turn off switching losses Turn on switching loss dominated by the body diode reverse recovery, usually worse Q rr and t rr compared to separate diodes used with IGBTs On state conduction modeled by just a resistance (Ron); higher voltage rated device has longer n region, and therefore higher on resistance At the rated current for a given device area, higher voltage drop and hence larger conduction losses Not competitive for voltage ratings exceeding 900 V Device of choice in power electronics for low power levels up to 1 10 kw, 100 khz to MHz f s 12
Emerging power semiconductor devices Specific ON resistance [cm2] V B = device breakdown voltage E c = critical electric field 13
GaN Structures Lateral device Vertical device 14
Reduced resistive voltage drops Much reduced stored charge, very low current tail or reverserecovery related switching losses Capability of operation at increased junction temperature 15
Introduction to thermal management IGBT module Example: Infineon FF150R12T4 1200V, 150A 4 5 3 1 6 4 5 7 2 6 7 3 2 1 16
Introduction to thermal management Temperature rise = Power dissipation * Thermal resistance 17
Introduction to thermal management 18
Example: 2010 Prius converter and inverter assembly* 27 kw DC DC converter, 60 kw inverter, 42 kw inverter 130 kg, 16 liters *Evaluation of the 2010 Toyota Prius Hybrid Electric Drive System, Oak Ridge National Lab 2011 report 19
20
DC DC Conversion in Electric Drivetrains Charger Drivetrain DC DC 12V battery, Lights, Electronics, HV to LV DC DC Active balancing DC DC Applications: Bidirectional drivetrain DC DC converter: power rating of the battery system (10 s of kw) Auxiliary high voltage DC to low voltage DC (12V), several kw Battery system active balancing: <10W per converter Charger: 1 kw 100 kw 21
Bidirectional Drivetrain DC DC Converter Introduction to efficient switched mode power conversion Steady state analysis: inductor volt seconds balance, capacitor charge balance Power semiconductor components: IGBTs, MOSFETs, diodes Modeling of losses Thermal management Control Simulations Reference: R.W.Erickson, D.Maksimovic, Fundamentals of Power Electronics, 2nd edition, Springer 2001. Available on line from campus network. Chapters 2, 3, 4, sections from Chapters 7, 8, 9, sections from Chapter 13 22
Next: AC motor drive subsystem Charger Drivetrain DC DC AC motor drive 12V battery, Lights, Electronics, HV to LV DC DC + Active balancing DC DC V bat + V bus AC machine Permanent magnet synchronous machine, induction machine Operation, losses and efficiency and dynamic model 3 phase DC to AC inverter Operation, losses and efficiency, dynamic model Electric drive: control 23